Service for transmitting a video signal on demand via an ISDN link

ABSTRACT

To provide an interactive video service, a system is disclosed comprising a video server (VOD), an integrated services digital network (ISDN), and customer premises equipment (END) with a video telephone (TEL). The video server (VOD) has a memory (MEMO) in which a number of video signals, e.g., newscasts, are stored, as well as a transmitting unit (SEN) and a receiving unit (EMP), by means of which it is connected with the video telephone (TEL) via the integrated services digital network (ISDN). Via the video telephone (TEL), the customer calls the video server (VOD) to establish a switched connection, and selects from among a number of video signals available. By means of a control unit (CTRL) in the video server (VOD), the selected video signal is read from the memory of the video server and transmitted in real time over the switched connection to the video telephone (TEL). The customer can release the connection at any time, whereby the transmission of the video signal is stoppped.

TECHNICAL FIELD

The present invention relates to a service for transmitting a videosignal and to a video server.

BACKGROUND OF INVENTION

Video servers are servers which have a number of video signals stored ina memory and which transmit selected video signals to their customers ondemand.

One possibility of transmitting video signals is known from U.S. Pat.No. 5,410,343. The customers inquire about video films, tapes, programs,or the like currently available from the video server via a digitaltelephone network, and select one of them. The selected video signal istransmitted from the video server over a broadband additional channel ofthe digital telephone network, and displayed to the customer on atelevision set. To provide the broadband additional channel, severaldigital-cross connect systems are necessary. Because of the nonuniformutilization of the broadband additional channels, the transmissioncapacity of the digital telephone network is not optimally utilized.Moreover, the selection of the video signal involves a considerableamount of technical complexity, since it requires a protocol adaptationfacility, a so-called video gateway, and a network management system.

DISCLOSURE OF INVENTION

It is therefore an object of the invention to transmit video signalswith less technical complexity.

According to a first aspect of the present invention, a service fortransmitting a video signal from a video server to a video telephonecomprises interconnecting the video server and the video telephone viaan integrated services digital network, wherein the video server iscalled via the video telephone to establish a switched connection,wherein via the video telephone a video signal is selected from among anumber of video signals available, and wherein the selected video signalis transmitted from the video server to the video telephone over theswitched connection.

In further accord with this first aspect of the present invention, thevideo telephone is connected to the integrated services digital networkvia a digital radio network, and the video telephone is located in amoving object.

In still further accord with the first aspect of the present invention,the selected video signal is transmitted in real time.

According still further to the first aspect of the present invention,the transmission of the selected video signal can be stopped byreleasing the switched connection via the video telephone.

According to a second aspect of the invention, a video server fortransmitting video signals comprises a transmitting unit, a receivingunit, a control unit, and a memory, wherein a number of video signalsare storable in the memory, wherein via the control unit individual onesof the video signals stored in the memory are selectable and feedable tothe transmitting unit, wherein the transmitting unit and the receivingunit are connectable to an integrated services digital network, whereinthe video server is callable via the receiving unit for theestablishment of a switched connection from the integrated servicesdigital network, and wherein in response to signals received at thereceiving unit, a stored video signal is selectable and transmittableover the switched connection into the integrated services digitalnetwork.

In further accord with this second aspect of the invention, the videoserver is called by dialing a number composed of a service number plusan additional number, and the additional number is based on anabbreviation of a name of the video server.

According to a third aspect of the present invention, a video telephonewhich has a slot for a chip card and a card-reading device and which canbe put into operation by means of a chip card with a code dependent on avideo server, has the capability to determine a call number of the videoserver via the card-reading device from the code dependent on the videoserver, and wherein establishment of a switched connection to the videoserver is made possible via the card-reading device by automatic dialingof the call number of the video server.

A special advantage of the invention is that video-on-demand service ismade possible via an existing digital telephone network.

Another advantage of the invention is that video-on-demand service canalso be offered in moving objects.

A further advantage is that through the additional service, thefunctionality of the integrated services digital network is extended, sothat the network is optimally utilized and becomes more attractive.

These and other objects, features and advantages of the presentinvention will become more apparent in light of the detailed descriptionof a best mode embodiment thereof, as illustrated in the accompanyingdrawing.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic representation of a first embodiment of a systemfor transmitting video signals, according to the present invention;

FIG. 2 is a schematic representation of a second embodiment of a systemfor transmitting video films; and

FIG. 3 shows a numeric keypad of a video telephone, according to thepresent invention.

BEST MODE FOR CARRYING OUT THE INVENTION

Referring to FIG. 1, a first embodiment of a system according to theinvention is illustrated. The system SYS for transmitting video signalscomprises a video server VOD, an integrated services digital networkISDN, customer premises equipment END, and a transmitter TV fortransmitting television signals.

The integrated services digital network ISDN is the so-called ISDN, inwhich information is transmitted in narrow-band bearer channels andsignaling channels. At an ISDN basic access, the customer premisesequipment is assigned, for example, two 64-kb/s bearer channels and one16-kb/s signaling channel.

The transmitter TV for transmitting television signals is, for example,the transmitter of the Suddeutscher Rundfunk (South German BroadcastingService), SDR, which feeds its television program into a broadband cabledistribution network, for example, thus transmitting it to a pluralityof customer premises equipments.

The customer premises equipment END comprises a video telephone TEL. Thevideo telephone TEL is known, for example, from a prospectus entitled"Alcatel 2838--Das Bildtelefon in Ihrem Buro", ("The Videotelephone inYour Office") 3/1995.

The video server VOD comprises a control unit CTRL, a memory MEMO, atransmitting unit SEN, and a receiving unit EMP. The control unit CTRLis, for example, a microprocessor or a digital signal processor, and thememory MEMO is, for example, a random-access memory.

The video server VOD is connected to the transmitter TV and, via theintegrated services digital network ISDN, to the video telephone TEL.The video telephone TEL is connected to the integrated services digitalnetwork ISDN via a 2×64 kb/s+1×16 kb/s ISDN basic access.

The memory MEMO holds a number of different video signals. Such a videosignal may, for example, be a newscast which was transmitted from thetransmitter TV and received and recorded by the control unit CTRL.During the transmission of newscasts, studio pictures are transmitted.Studio pictures show little change in information from picture topicture. If only the change in information from picture to picture istransmitted instead of the entire picture, it is possible to transmitthe newscast over a narrow-band channel, e.g., a 64-kb/s channel.Another video signal shows, for example, a landscape shot as a promotionfilm of a travel agency or as information on the current weathersituation in a skiing area.

The video server VOD provides interactive video service for transmittingselected video signals from the video server VOD to the video telephoneTEL of the customer premises equipment. The customer dials the number ofthe video server VOD via the video telephone TEL to establish a switchedconnection. Via the signaling channel and via an exchange of theintegrated services digital network ISDN, the switched connectionbetween customer premises equipment END and video server VOD isestablished. The switched connection contains the two 64-kb/s channels.One of the two 64-kb/s channels serves to transmit pictures, and theother serves to transmit speech, i.e., the sound associated with thepictures. When the switched connection has been established, the videoserver VOD transmits a list of the different video signals in the formof a menu to the customer premises equipment END. On the screen of thevideo telephone TEL, video signal titles arranged according to subject,for example, are displayed with the associated selection number.Subjects are, for example, latest news, travel, or language course. Thedesired selection number is entered by the customer via the numerickeypad of the video telephone TEL and transmitted over the signalingchannel to the video server VOD. The video server VOD receives theselection number via the receiving unit EMP and passes it on to thecontrol unit CTRL. The control unit CTRL selects the video signalbelonging to the selection number from the video signals stored in thememory MEMO, and transmits it in real time via the transmitting unit SENand the two 64-kb/s channels to the video telephone TEL. Throughout thetransmission, the switched connection between customer premisesequipment END and video server VOD is maintained. The switchedconnection can be released by the customer premises equipment END at anytime simply by replacing the handset of the video telephone TEL like atthe end of a normal telephone call. Furthermore, by entering apredetermined number at the video telephone TEL, the transmission of thevideo signal can be stopped and the switched connections simultaneouslymaintained to select another video signal via the menu then appearing.When the transmission of the selected video signal has been completed,the video server VOD transmits the menu to the customer premisesequipment. If no data is entered after a predetermined time, theswitched connection will be released.

Referring now to FIG. 2, a second embodiment of the system according tothe invention is illustrated. The system SYS for transmitting videosignals comprises a transmitter TV for transmitting television signals,a satellite SAT, a video server VOD, an integrated services digitalnetwork ISDN, a digital radio network GSM, and a moving object ZUG.

The transmitter TV for transmitting television signals is, for example,the transmitter of a television organization which transmits itstelevision programs over a radio link to the satellite SAT, whichtransmits them back to earth, so that they can be received by a numberof customer premises equipments.

The video server VOD is of a design comparable to that of the videoserver of FIG. 1. It comprises a control unit, a memory, a transmittingunit, a receiving unit, and an additional receiving facility forreceiving the television programs transmitted via the satellite SAT. Theintegrated services digital network ISDN is the so-called ISDN of FIG.1.

The digital radio network GSM is a cellular mobile radio network basedon the GSM standard; "GSM" stands for "Global System for MobileCommunication". The digital radio network GSM comprises a base stationBTS, a base station controller BSC, and a mobile switching center MSC.The mobile switching center MSC is connectable to several base stationcontrollers. The base station controller BSC is connectable to severalbase stations. The base station BTS is connected to the integratedservices digital network ISDN via the base station controller BSC andthe mobile switching center MSC.

As one embodiment of the moving object ZUG, a car of a railroad trainhas been chosen. The moving object ZUG may also be a motor vehicle, forexample. The railroad car ZUG comprises a unit UNIT for receiving theradio signals transmitted via the base station BTS, for converting theseradio signals into signals capable of being processed by a videotelephone, and for converting the signals from the video telephone intoradio signals conforming to the GSM standard. The railroad car ZUGfurther contains a video telephone TEL.

The video telephone TEL corresponds to the video telephone of FIG. 1except it additionally has a slot for a chip card and a card-readingunit. Via the card-reading unit, the video telephone TEL can be locked.When there is no chip card in the slot, the video telephone TEL islocked. Only the insertion of a chip card CARD with a code dependent onthe video server VOD will unlock the video telephone TEL, so that thelatter can be put into operation and a switched connection can beestablished to the respective video server. The code dependent on therespective video server (VOD) contains the call number of the respectivevideo server (VOD). The call number is entered via the card-readingdevice and dialed automatically, whereby a switched connection to therespective video server (VOD) is established. During the transmission ofa selected video signal, the current charge may be indicated, e.g., onthe screen of the video telephone.

From the video telephone TEL, a switched connection to the video serverVOD is established via the digital radio network GSM and the integratedservices digital network ISDN. After establishment of the connection, aparticular video signal is selected and transmitted in a manner similarto that described with reference to FIG. 1.

The video telephone TEL is incorporated in the back of a chair, forexample, so that it is easy for a passenger of the railroad train tooperate the phone.

FIG. 3 shows an alphanumeric keypad which can be used for the videotelephone of FIG. 1 and the video telephone of FIG. 2.

The keys with digits 2 to 0 are additionally assigned the letters A-Z ofthe alphabet. For example, the key with digit 2 is assigned the lettersA, B, C, and the key with digit 6 is assigned the letters M and N.

Each video server VOD has a video server name. A video server is named,for example, after a television organization, such as "Zweites DeutschesFernsehen" (Second German Television). As an abbreviation of the videoserver name, ZDF will then be dialed, for example. If the customer wantsto establish a switched connection to the video server VOD, e.g., ZDF,he or she will dial a service number plus an additional number which isdependent on the abbreviation of the video server name.

To access the video server VOD of ZDF, for example, the customer willdial the number 0190 as a service number plus VODZDF, which correspondsto the additional number 803033, to establish a connection to the videoserver VOD.

If the customer frequently selects the same numbers for the respectivesubjects, e.g., 100 for the latest news, in the menu of the video serverVOD, he or she may also, after knowledge of the assignment, select aparticular video signal by direct dialing, i.e., without taking theroute via the menu. Thus, the customer will be presented with the latestnews from the video server VOD of CNN by entering 0190 VOD CNN 100 athis or her video telephone, which corresponds to the dialed digits 0190803 226 100.

Both embodiments use the integrated services digital network ISDN, inwhich information is transmitted over narrow-band channels. By"narrow-band", a transmission capacity of 9.6 kb/s to 2 Mb/s isunderstood. If a transmission capacity of 9.6 kb/s, as is used, forexample, in digital radio networks, is not sufficient to transmit theselected video signal, a switched connection can be established whichcombines several channels, so that seven times 9.6 kb/s=67.3 kb/stransmission capacity, for example, are available.

Although the invention has been shown and described with respect to abest mode embodiment thereof, it should be understood by those skilledin the art that the foregoing and various other changes, omissions andadditions in the form and detail thereof may be made therein withoutdeparting from the spirit and scope of the invention.

We claim:
 1. A video server (VOD) for transmitting video signals,comprising a transmitting unit (SEN), a receiving unit (EMP), a controlunit (CTRL), and a memory (MEMO),wherein a number of video signals arestorable in the memory (MEMO), wherein via the control unit (CTRL)individual ones of the video signals stored in the memory (MEMO) areselectable and feedable to the transmitting unit (SEN), wherein thetransmitting unit (SEN) and the receiving unit (EMP) are connectable toan integrated services digital network (ISDN), wherein the video server(VOD) is callable via the receiving unit (EMP) for the establishment ofa switched connection from the integrated services digital network(ISDN), wherein the video server (VOD) is called by dialing a numbercomposed of a service number plus an additional number, and that theadditional number is based on an abbreviation of a name (ARD) of thevideo server, and wherein in response to signals received at thereceiving unit (EMP). a stored video signal is selectable andtransmittable over the switched connection into the integrated servicesdigital network (ISDN).